/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

package fr.loof.fonzie.keywords;

import java.util.ListIterator;

import fr.loof.fonzie.parsers.Constraint;
import fr.loof.fonzie.parsers.KeyWord;
import fr.loof.fonzie.parsers.QueryElement;
import fr.loof.fonzie.parsers.QueryPostProcessor;
import fr.loof.fonzie.parsers.Property.Decorator;

public class Not
    extends KeyWord
    implements QueryPostProcessor, Constraint
{
    protected String getOperator()
    {
        return "not";
    }

    @Override
    public boolean postProcess( ListIterator<QueryElement> elements )
    {
        boolean changed = false;

        if ( elements.hasPrevious() )
        {
            QueryElement previous = elements.previous();
            elements.next();
            if ( previous instanceof Inversable )
            {
                changed |= ( (Inversable) previous ).inverse();
                elements.previous();
                elements.remove();
            }
        }

        if ( elements.hasNext() )
        {
            QueryElement next = elements.next();
            elements.previous();
            if ( next instanceof Inversable )
            {
                changed |= ( (Inversable) next ).inverse();
                elements.previous();
                elements.remove();
            }
            if ( next instanceof Decorator )
            {
                // switch
                elements.remove();
                elements.previous();
                elements.add( next );
                changed = true;
            }
        }
        else
        {
            // not without constraint
            elements.add( new Equals() );
            changed = true;
        }
        return changed;

    }
}